name `rai` abstractions differently to `ros2` abstractions

[boczekbartek]

Is your feature request related to a problem? Please describe. ros2 users are used to ros2 abstractions. Currently, it is easy to confuse some concepts. For example ros2.Node and langgraph.Node can be confused.

Describe the solution you'd like Keep ros2 naming and rename rai abstractions.

Describe alternatives you've considered

Additional context ros2 docs: https://docs.ros.org/en/jazzy/index.html